This nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 91113890 filed in Taiwan on Jun. 25, 2002, which is herein incorporated by reference.
1. Field of the Invention
This invention relates to a material for spacer bonding, particularly to an SOG (Spin on Glass) material for spacer anodic bonding, and to a method of preparing the same.
2. Description of the Prior Art
The technology of micromachining uses semiconductor processes to manufacture mechanical elements, such as minute cantilevers, thin sheets, gears, and valves. The size of these elements can be even smaller than one micrometer (one millionth meter). Therefore, micromachining can be used to manufacture motors having dimensions equal to the diameter of a strand of hair.
The technology of microelectromechanical system, or MEMS, has the advantages as follows:
(1) mechanical structures and electronic circuits can be integrated;
(2) the costs for manufacturing the products can be reduced and the quality can be maintained constantly by batch fabrication; and
(3) the size of products can be reduced while the precision is increased.
Therefore, MEMS technology can be used to manufacture many sensors and actuators at low cost. Currently, commercial products produced through the utilization of MEMS technology are, for example, pressure gages, accelerometers, biosensors, ink jet printer heads, a number of disposable medical instruments, and the like. In addition to its many present applications, MEMS technology may prove useful to the development of critical industries such as defense and biology. Thus, many advanced countries are investing heavily in this technology.
The technique of bonding to substrates is very important to MEMS. Recently, the bonding techniques have diversified, and among them, the application of anodic bonding in microsensor, elements, micromechanical elements or field emission display (FED) elements has produced remarkable results. Accordingly, developing new material for anodic bonding will undoubtedly become one of the most important research targets in this field.
In view of the above, the main object of the invention is to provide an SOG material for spacer anodic bonding in FED processes. The SOG material includes:
0.1xcx9c3 wt % of tetraethyl orthosilicate (TEOS);
0.1xcx9c5 wt % of methyl triethyl orthosilicate,(MTEOS);
20xcx9c30 wt % of ethanol;
0.1xcx9c2 wt % of acetic acid solution containing alkali metal ions; and
0.1xcx9c10 wt % of water; wherein
the solid content of alkali metal elements in the acetic acid solution containing alkali metal ions mentioned above is 5%-60% based on the weight of the acetic acid solution containing alkali metal ions, and the pH value of the SOG material is between about 4 and 6.
The bonding strength between spacer and substrate achieved by anodic bonding can be greatly increased with the solid content of alkali metal elements by the use of the SOG material for spacer anodic bonding of this invention.
Another object of the invention is to provide a method of preparing an SOG material for spacer anodic bonding, comprising the steps of:
(i) mixing 0.1xcx9c3 wt % of tetraethyl orthosilicate (TEOS), 0.1xcx9c5 wt % of methyl triethyl orthosilicate (MTEOS) and 20xcx9c30 wt % of ethanol to obtain a first mixture; and
(ii) mixing the first mixture and a mixture of 0.1xcx9c2 wt % of acetic acid solution containing alkali metal ions and 0.1xcx9c10 wt % of water to form the SOG material; wherein
the solid content of alkali metal elements in the acetic acid solution containing alkali metal ions is 5%xcx9c60% based on the weight of the acetic acid solution containing alkali metal ions, and the pH value of the SOG material is 4xcx9c6.
The following example is intended to illustrate the invention more fully without limiting its scope, since numerous modifications and variations will be apparent to those skilled in this art.